Kuro no Shoukanshi (Black Summoner)

Losing his memories, the curtains of the story of alternate world transfer of the MC rises. After the transfer his name changes to Kelvin. While steadily levelling, he adds new subordinates by mastering his skill. And by the time he noticed it, he had obtained overwhelming power. Where will our MC be heading off to?
Publisher: Overlap
Status : Ongoing ( 7 volumes)
Manga : YesLNDB

Protagonist trades his memories for abilities in order to get an edge on everybody else. He also contracted Goddess that summoned him as his familiar. Year prior main character appearance, goddess summoned 4 heroes to the world in order to fight against the next demon lord. Since goddess worked for over one thousand years without a break, she got permission from other gods to take vacation. Apparently she decided to use protagonist for her own convenience while taking a break as his familiar. That, or he fell in love with her and begged her to become his familiar, nobody knows, because main character traded away his memories. She cannot be easily summoned due to absurd mana requirement.
So far the story is interesting enough on its own, it seem to be setting up main character to be at odds with the other heroes in the world, since MC contracted next in line to be the demon lord as his familiar. Would love to read the rest :)